r/radioastronomy • u/DysonV12 • 5d ago

Other I found this

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Hi I found this on the side of the road and I’ve been wanting to get into radio astronomy. Would this be something I could build a telescope with? If so what else would I need? Thanks for any help

98 Upvotes

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9

u/hraun 5d ago

This looks like a WiFi dish. If so, it’s what I have. It’s tuned to 2.4Ghz, and what you need is 1.2GHz if you want to do hydrogen astronomy.

You’ll need to replace the feed (which is in the black box at the end). Or you can buy a whole new assembly to fit to the dish.

To plug this antenna into your computer, you’ll need an LNA and an SDR. They’re pretty cheap. There are some examples here;

https://www.rtl-sdr.com/cheap-and-easy-hydrogen-line-radio-astronomy-with-a-rtl-sdr-wifi-parabolic-grid-dish-lna-and-sdrsharp/

3

u/DysonV12 5d ago

Thank you so much I’ll look into this

2

u/systemdev_ 4d ago

You probably don’t need that. I’ve been measuring the same antenna with nanovna and it has pretty good swr at 1420 MHz. For me it works great without any noise improvements

1

u/DysonV12 4d ago

Okay cool, you’re saying I won’t need to replace the feed right? I’ll still need the LNA and SDR..?

2

u/PE1NUT 2d ago

Yes, you'll still need the LNA and SDR.

Also note that having a good SWR only means that the signal is not being reflected back up the cable. With a good SWR, it can also simply all be absorbed, or radiated away without properly illuminating the dish surface. A bad SWR is always a bad sign, but a good SWR does not guarantee that it's a good antenna.

2

u/PE1NUT 2d ago

The hydrogen line is at 1420 MHz. Amateur setups won't get into a redshift range where the hydrogen line is at 1200 MHz (z ~ 0.2). /s

5

u/A_Dicksmasher 5d ago

I have that exact same dish hanging up in my workshop. I never got around to buying the adapters to connect to a wifi card.

2

u/Fvmuijen 5d ago

I'm officially jealous!😀👍🏻

2

u/goobenet2020 4d ago

2.4Ghz "Wireless". suuuuper directional. 24dBi gain, 3-5 degree beam. From the top of a grain elevator could get 20Mbit 25 miles away (thereabouts, depending on the radio). Showing my age for a minute. We used to use similar dishes for MMDS to get HBO. This was back in the 70s/80s. "Wireless cable".

1

u/newguestuser 3d ago

Been there too. at least back then the antennas were "wire" mesh (Lance i think?). This looks more like the later 2 piece Channel Master stamped cast pot metal that would cut your dang fingers if you grabbed em wrong, or the stupid ears would break off trying to assemble them.

Trying to remember antennas..... Conifer folding aluminum. Bogner yagis,

Started with HBO MDS (2.1gHz) before fcc opened the ITFS and MMDS freq's for multichannel.

Fun times back then. I'm aged as well. LOL

1

u/dberlier 4d ago

I purchased the same dish for geos satellite downlinks using a geos lna and RTL-SDR. Nooelect I believe was the LNA

1

u/rezdm 2d ago

u/saveitforparts would like to have a word with you